Loading patent…
AssigneeAston University
InventorsIan John Murgatroyd, Catherine Anne Sugden, Karen Elizabeth Chisholm
Estimating the term…
Apparatus (10) for interrogating an optical signal (not shown) propagating in an optical waveguide, such as an optical fibre, having an input section (12) and a second section (14) through which light entering from the input section (12) will subsequently propagate. The second section (14) includes a grating portion, such as a tilted chirped fibre Bragg grating (16). The grating (16) causes at least part of the optical signal to be coupled out of the optical fibre, through the fibre cladding. A photodetector (18) is provided generally alongside the grating (16). The photodetector (18) is arranged to collect and detect substantially all of the outcoupled optical signal. The relationship between the optical power outcoupled by the grating (16) and the wavelength of the optical signal is known, allowing a measurement of the outcoupled optical power to be used to determine the wavelength of the optical signal propagating through the grating (16).
Apparatus for interrogating an optical signal propagating in an optical waveguide, the apparatus comprising an optical waveguide having a grating portion along which the refractive index of the waveguide varies periodically, the said variation giving the grating portion a spectral profile having a first region across which the transmitted optical power is substantially constant as a function of wavelength and a second region across which the transmitted optical power changes as a function of wavelength, the said variation of refractive index causing at least part of the optical signal to be coupled out of the grating portion of the waveguide, and first optical means operable to measure the optical power of an outcoupled optical signal.
Apparatus according to any preceding claim in which the first and second wavelength ranges are substantially adjacent in wavelength space.
Apparatus according to any preceding claim in which the optical waveguide is an optical fibre.
Apparatus according to any preceding claim in which the first optical means comprises photodetector means.
Apparatus for determining the wavelength of an optical signal propagating in an optical waveguide, the apparatus comprising apparatus for interrogating an optical signal propagating in an optical waveguide, the apparatus being according to any preceding claim, and utilising the second region of the spectral profile of the grating portion to cause at least part of the optical signal to be coupled out, and means for determining the total power of the optical signal to be interrogated, the wavelength of the said optical signal being proportional to the ratio of the power of the outcoupled optical signal to the total power of the optical signal.
Apparatus for interrogating an optical signal propagating in an optical waveguide substantially as described above with reference to the accompanying drawings.
Apparatus for determining the wavelength of an optical signal propagating in an optical waveguide substantially as described above with reference to FIGS. 4 to 7 and 11 of the accompanying drawings.
Apparatus for stabilising the wavelength of a laser beam emitted by an optical waveguide coupled laser substantially as described above with reference to FIGS. 8a and 8b of the accompanying drawings.
Apparatus for determining the value of a first parameter sensed by an in-fibre sensor, by interrogating an optical signal returned by the sensor, substantially as described above with reference to FIGS. 9 and 10 of the accompanying drawings.
Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.
Dependencies are inferred from the claim text.